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HL: Fachverband Halbleiterphysik

HL 55: GaN: preparation and characterization II

HL 55.12: Talk

Friday, February 29, 2008, 13:30–13:45, ER 164

SNOM studies of GaInN/GaN and GaN/AlGaN QW structures — •Peter Clodius, Frank Hitzel, Daniel Fuhrmann, Carsten Netzel, Holger Jönen, Lars Hoffmann, Heiko Bremers, Uwe Rossow, and Andreas Hangleiter — Technical University of Braunschweig, Institute of Applied Physics

Blue or green light emitting GaInN/GaN-based quantum well (QW) structures achieve quite high internal quantum efficiencies (IQE) at room temperature. In contrast In-free QW-structures based on GaN/AlGaN emitting in the UV-range suffer from low IQE values. This is caused by the high density of defects in this material and nonradiative recombination occuring at these defects. We present studies of photoluminescence with a high spatial resolution, performed on GaInN/GaN and GaN/AlGaN QW structures. The measurements were performed using a scanning near-field optical microscope (SNOM). The measurements on the GaInN/GaN QWs show that nearly every line defect in these structures is decorated by a so-called V-pit (an inverted hexagonal pyramid with (1011) planes as sidewalls). On the sidewalls of these pits the growth rate of the QW is reduced, which leads to thinner QWs on the facets than on the c-plane. These thinner QWs form a barrier which prevents carriers from nonradiative recombination at the line defects. We investigate short wavelength GaInN/GaN and GaN/AlGaN structures with the aim of clarifying whether such pits play a role in such structures as well.